Distributed optical fibre sensing is a well known approach to providing information about environmental conditions surrounding a sensing optical fibre. Fully-distributed sensing in principle provides spatially resolved information from every point along the fibre. Variables that can be sensed include temperature, static strain, pressure, and vibration.
One such technique detects variations in refractive index, induced by a physical forcing such as vibration, in the coherent Rayleigh backscatter interference profile of light backscattered within a sensing optical fibre interrogated by an optical source of limited bandwidth. Such Rayleigh backscatter interference profiles arise from interference between the many components of the backscattered light originating from different points along a portion of the sensing optical fibre illuminated by the optical source. Such techniques are described, for example, in WO2008/056143.
It would be desirable to address problems and limitations of the related prior art.